Experimental studies were carried out in order to evaluate the coefficient of convective heat transfer, h, an impingement air cooling method was designed for this target. Studies were carried out to determine the Convective Heat Transfer Coefficient, h, under multiple jets of impinging cold air on a target heated flat plate. Tests were run with air- distribution plates with hole diameters, d, of 1.5mm, 2.0mm, 2.5mm and 3.0mm. The target plate is a carbon-steel flat plate of 6mm thickness, instrumented with a total of three Chromel-Alumel K-type thermocouples. The plate is electrically heated using a variable supply current input. Test were run at various cooling air flow rate G, between 1.0kg/m3, sec to 3.0kg/m3, sec. Distribution plate-to-target plate distance Z(mm), was varied between 100mm to 200mm. Heat input to the target plate Q Watt, was varied to give a heat flux rate between 10 to 100 watts. Results obtained were reduced and analyzed by evaluating for the dependence of h on the impingement jet diameter, Jet Reynolds Number, and the coolant mass flow rate G. Based on the results obtained, considerations were done on the effect of impingement gap Z on convective heat transfer coefficient h, w/m2,oC.
Keywords: Cooling, Heat transfer Coefficient, Impingement, Nusselt Number, Prandtl Number, Reynolds Number
